PRIN 2_L11_Arterial Puncture

• arterial puncture - used to collect blood specimen for ABG analysis to manage cardiopulmonary disorders and maintain acid-base balance of the body

  • arterial blood is the ideal specimen for respiratory function evaluation due to the consistency of its composition and high oxygen content
• tests requiring arterial blood:

  • blood gas
  • lactic acid
  • ammonia
• components of arterial blood gases:

  • pCO2
  • pO2
  • pH
• conditions requiring ABG measurement:

  • respiratory diseases
  • metabolic diseases
• partial pressure of oxygen (pO2) - measures the pressure of O2 dissolved in the blood

  • normal value: 75-100 mmHg
• partial pressure of carbon dioxide (pCO2) - measures the pressure of CO3 dissolved in the blood

  • normal value: 35-45 mmHg
• pH - measures the acidity or alkalinity of the blood (indicates acidosis or alkalosis)

  • normal value: 7.35-7.45
• bicarbonate (HCO3) - buffers the blood to prevent acidosis or alkalosis

  • normal value: 20-29 mEq/L
• oxygen content (ctO2) - measures the amount of O2 in the blood

  • normal value: 15-22 mL/100 mL of blood
• oxygen saturation (O2Sat) - measures how much of the hemoglobin in the red blood cells is carrying O2

  • normal value: 95-100%
• personnel performing arterial punctures qualifications (training)

  • complications associated with arterial puncture
  • precautions taken to ensure a safe procedure
  • sample handling procedures to prevent alteration of test results
  • correct puncture technique
  • supervised puncture performance
• personnel performing arterial punctures

  • physicians
  • nurses
  • medical laboratory scientists
  • respiratory scientists
  • emergency medical personnel
  • senior phlebotomists
• sites of puncture

  • radial artery - most preferred site
  • femoral artery
  • brachial artery
• order of preference for arterial puncture

  1. radial
  2. brachial
  3. femoral
• radial artery - ulnar artery can provide collateral circulation

  • close to the wrist; easily accessible
  • pressure can be easily applied
  • less chance of hematoma
  • difficult to locate in patients with hypovolemia or low cardiac output
• brachial artery - deeper, near median nerve, lies in soft tissue

  • lies close to the median nerve; risk of pain and nerve damage
  • increased risk of hematoma formation
• femoral artery - large and easily palpated and punctured

  • sometimes only site where arterial sampling is possible
  • poor collateral circulation
  • increased risk of infection because of location and pubic hair
  • risk of dislodging plaque build-up from inner artery walls
• why is radial artery the arterial puncture site of choice

  1. ulnar artery can provide collateral circulation
  2. lies close to the surface of the wrist and is easily accessible
  3. can be easily compressed against the wrist ligaments, less chance of hematoma
• to be acceptable as a puncture site, an artery must be:

  1. large enough to accept at least 25-gauge needle
  2. located near the skin surface so that deep puncture is not required
  3. in an area where injury to surrounding tissues will not be critical
  4. located in an area where other arteries are present to supply blood in case the punctures artery is damaged
• arterial puncture equipment

  • syringes: preanticoagulated, plastic
  • type: hypodermic
  • size: 1-5 mL
  • needles: 20-25 gauge, 5/8-1.5 inches
• heparin - used to coat the plastic syringes to be tested within 30 minutes

  • glass syringes are used for tests longer than 30 minutes, lubricated, and heparinized by collector
  • tightly fitting cap for syringe Luer tip
• gauge of needle required for arterial puncture

  • brachial artery uses 18-20 needle gauge
  • radial artery uses 23-25 needle gauge
• additional supplies

  • crushed ice slurry for longer than 30 minutes specimens
  • povidone-iodine, chlorhexidine for site cleaning
  • alcohol pads to remove iodine if needed
  • gauze and pressure dressings
  • local anesthetic, prepared by collector
• arterial puncture procedure (phlebotomist and patient prep)

  1. examination of a requisition form
  2. collection of equipment and supplies
  3. patient assessment

  
• steady state - 20 to 30 minutes of receiving specified amount of oxygen and have refrained from exercise

  • best time to collect arterial samples
  • do not collect samples from agitated patients
  • should be in relaxed state with normal breathing for at least 5 minutes
• collateral circulation - alternative source of blood supply around a blocked artery or vein
• major complications of arterial puncture include

  • thrombosis
  • hemorrhage
  • possible infection
• unacceptable sites during arterial puncture

  1. irritated areas
  2. edematous
  3. near a wound or in an area of arteriovenous (AV) shunt or fistula
• the amount of anticoagulant should be 0.05 mL liquid heparin (1000 IU/mL) for each milliliter of blood
• modified allen test - determine ulnar artery collateral circulation

  • performed prior to arterial puncture
• modified allen test procedure

  1. Positions patient’s wrist and makes fist
  2. Compress radial and ulnar arteries
  3. Patient opens fist → palm should blanch
  4. Release pressure from ulnar artery
  5. Observe color of patient’s palm
  6. Positive test results = color returns to palm
  7. Negative test results = palm remains blanched
• Aseptic cleansing procedure

  • Higher risk of infection using an artery
  • Use povidone iodine / chlorhexidine gluconate (air dry)
• Injection of local anesthetic may be administered

  • Lidocaine - Just under the skin, or surrounding tissue
  • Wait for anesthetic effect, 2 to 5 minutes  (effect begins to wear off in 15 to 20 minutes)
• performing the puncture

  1. relocating the artery: cleansed finger
  2. positioning of fingers: non-dominant direct over site
  3. puncture depth: 5-10 mm
  4. angle: 30-45 degrees, hold syringe like dart
• recommended angles

  • radial artery: 30-45 degrees
  • brachial artery: 45-60 degrees
  • femoral: 90 degrees
• appearance of blood in the syringe

  • color: bright red
  • pulsation: blood enters syringe without help
• performing the puncture (cont.)

  1. removal of needle
  2. application of direct pressure by the phlebotomist; firm for at least 5 minutes (AC therapy > 5 mins)
• CLSI guidelines

  • Samples that can be analyzed within 30 minutes should be collected in plastic syringes and not placed in ice
  • When lactate (lactic acid) is requested; samples are placed on ice immediately
  • Samples that cannot be analyzed within 30 mins. must be collected in glass syringe and are placed in ice
• sampling errors

  • Air bubbles were not expelled from the sample
  • Processing exceeded optimal time
  • Sample was not mixed properly or immediately
  • Syringe was used improperly
  • Venous blood was obtained by mistake
  • Improper anticoagulant was used Incorrect volume of heparin was used
• criteria for rejection of ABG specimen

  • Air bubbles are found in the specimen
  • The specimen has clotted
  • The specimen has hemolyzed
  • The submitted specimen did not comply with the proper labeling requirement
  • The prescribed transportation temperature for the specimen was not met
  • The specimen did not meet the required volume or QNS
  • It took so much time for the specimen to reach the laboratory The wrong type of syringe was used